The goals of this project are: (1) to determine the minimum dose of intratympanic gentamicin necessary to control vertigo in unilateral Meniere's disease, and (2) to determine what effects this dose has on the structure and function of the vestibular organs of the inner ear. Multiple intratympanic injections, if spaced 1 week apart and halted at the first signs of loss of vestibular function, can control vertigo in >90% of patients with no greater hearing loss than the disease itself causes. We will conduct a clinical trial in which gentamicin will be given every 2 weeks until vertigo is controlled. We wish to determine if lower total doses can control vertigo yet preserve some vestibular function as measured by 3-dimensional vestibulo-ocular reflexes, vestibular-evoked myogenic potentials, subjective visual vertical, and caloric tests. By following patients for one year we can also determine if some vestibular function returns over time. We also want to know what these doses of gentamicin do to the vestibular part of the inner ear and the vestibular nerve afferents. Are all or most of the hair cells destroyed? Do the vestibular nerve afferents stop responding? Is there some return of some function over time? If so, why? Do hair cells recover, do afferents become more sensitive, or does the brain adjust its responses to make up for the peripheral loss. These questions will be answered in an animal model. The candidate has a background in vestibular physiology and now seeks a long-term career in academic otolaryngology, focusing physiologic principles on clinical vestibular problems. The short-term goals are to master the fundamentals of clinical trial design and analysis, 3D eye movements, and afferent neurophysiology. Johns Hopkins is uniquely suited to this training because it has a core group devoted to vestibular research, and the mentor's laboratory has successfully used all of the techniques required.